Posix Timezone format

Paul Koning Paul_Koning at Dell.com
Tue Dec 2 20:52:20 UTC 2008

>>>>> "Guy" == Guy Harris <guy at alum.mit.edu> writes:

 Guy> On Nov 13, 2008, at 4:48 PM, Louis Guindon wrote:

 >> This application is aimed for an embedded platform where a limited
 >> set of Linux functionalities is available. Uclibc is used on the
 >> platform and the /etc/timezone and the whole zoneinfo directory
 >> tree are not supported.

 Guy> That's unfortunate - my mobile phone has (at least in the first
 Guy> OS release, according to a list of files given by its
 Guy> jailbreakers) the full Olson timezone database on it.  (Then
 Guy> again, my mobile phone apparently has 128MB of main memory, and
 Guy> has 8GB of flash memory; maybe your embedded platform is a bit
 Guy> smaller.)

It doesn't take much memory to store the Olson database if you tweak
zic to omit any historic data.  In other words, if you need to show
current time, or perhaps timestamps going back to V1.0 release which
is a few years ago, that's only a small number of bits.  The reason is
that there are several hundred zone names but the vast majority
duplicate data for another zone, IF you keep only recent data.  If you
include all the history then there's very little duplication -- but
typically that non-duplicate entry is one from a century ago...

(That might be a nice standard feature for zic -- a switch that says
"keep only data from this date forward".


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